Cross-scale Drivers of Natural Disturbances Prone to Anthropogenic Amplification: The Dynamics of Bark Beetle Eruptions

I nteractions between plants and insects encompass half of all ecological relationships Understanding the dynamics of eruptive species can provide valuable insights into fundamental ecological processes such as ecosystem disturbance, multitrophic interactions, symbioses, chemical signaling, and the selective pressures driving coevolution. Eruptive species are also important systems for studying economically and environmentally damaging consequences of anthropogenic activities. To better understand these systems, we require more knowledge of how processes at different biological levels and spatiotemporal scales interact. In many cases, emergent patterns cannot be predicted even when lowerlevel mechanisms are well characterized Likewise, underlying mechanisms inferred from higher-level patterns can be obscured or incorrect when key cross-scale interactions and thresholds are not identified We approach this problem by exploring one system in depth, using information from biochemical-through landscape-level mechanisms to improve linkages of pattern with process. We illustrate how this approach can serve as a general model for improved understanding of ecological processes by which (a) cross-scale interactions, feedback, and thresholds both contribute to and constrain eruptive dynamics, and (b) anthropogenic activities interact with endogenous drivers to alter system behavior and generate fundamental regime shifts. Regime shifts have been defined as abrupt changes into different domains and trajectories beyond which prior controls no longer function (Scheffer and